A Sumatran tiger named "Malea" cleans one of her cubs in their enclosure at the zoo in the central German city of Frankfurt am Main on May 25, 2011.

A Sumatran tiger named "Malea" cleans one of her cubs in their enclosure at the zoo in the central German city of Frankfurt am Main on May 25, 2011.

Photo: Boris Roessler, AFP / Getty Images

A Sumatran tiger named "Malea" cleans one of her cubs in... Photo-1883537.33301 - SFGate

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More than 18,000 cubic feet per second of water flow over Shoshone Falls on Saturday May 21, 2011 in Twin Falls, Idaho. Wet weather and delayed snowmelt have combined to make a spectacular sight for visitors to Shoshone Falls in southern Idaho. less

More than 18,000 cubic feet per second of water flow over Shoshone Falls on Saturday May 21, 2011 in Twin Falls, Idaho. Wet weather and delayed snowmelt have combined to make a spectacular sight for visitors ... more

Photo: Ashley Smith, Times-News

More than 18,000 cubic feet per second of water flow over Shoshone... Photo-1883538.33301 - SFGate

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US President Barack Obama (L) high-fives with British Prime Minister David Cameron (R) as they play table tennis with students of the Globe Academy school in London, on May 24, 2011.

US President Barack Obama (L) high-fives with British Prime Minister David Cameron (R) as they play table tennis with students of the Globe Academy school in London, on May 24, 2011.

Photo: Jewel Samad, AFP / Getty Images

US President Barack Obama (L) high-fives with British Prime... Photo-1883539.33301 - SFGate

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In a May 24, 2011 photo, Amish men stop to speak with neighbors while traveling home at dusk in their buggy near Maysville, Ky.

In a May 24, 2011 photo, Amish men stop to speak with neighbors while traveling home at dusk in their buggy near Maysville, Ky.

Photo: Terry Prather, The Ledger Independent

In a May 24, 2011 photo, Amish men stop to speak with neighbors... Photo-1883540.33301 - SFGate

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Taboola Gallery Frame Item-85307.33301 - SFGate

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Eighteen-day-old pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) makes his first public appearance with its 29-year-old mother Dina at the Bratislava zoo on May 24, 2011. The father is four-year-old Paul brought from the Berlin atthe age of one. TOPSHOTS less

Eighteen-day-old pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) makes his first public appearance with its 29-year-old mother Dina at the Bratislava zoo on May 24, 2011. The father is ... more

Eighteen-day-old pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) makes his first public appearance with its 29-year-old mother Dina (not pictured) at the Bratislava zoo on May 24, 2011. The father is four-year-old Paul brought fromthe Berlin zoo at the age of one. less

Eighteen-day-old pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) makes his first public appearance with its 29-year-old mother Dina (not pictured) at the Bratislava zoo on May 24, 2011. ... more

In a May 24, 2011 photo, electric wires shoot sparks into the air as lighting strikes nearby when heavy storm clouds move into the Hampton Roads area Tuesday afternoon in Norfolk, Va. Heavy rain with gusty wind and hail caused much damages throughout thearea. less

In a May 24, 2011 photo, electric wires shoot sparks into the air as lighting strikes nearby when heavy storm clouds move into the Hampton Roads area Tuesday afternoon in Norfolk, Va. Heavy rain with gusty wind ... more

Photo: Hyunsoo Leo Kim, The Virginian-Pilot

In a May 24, 2011 photo, electric wires shoot sparks into the air... Photo-1883543.33301 - SFGate

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A monkey cools off in a water tub on a hot summer afternoon in Jammu, India, Wednesday, May 25, 2011.

A monkey cools off in a water tub on a hot summer afternoon in Jammu, India, Wednesday, May 25, 2011.

Photo: Channi Anand, AP

A monkey cools off in a water tub on a hot summer afternoon in... Photo-1883544.33301 - SFGate

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Taboola Gallery Frame Item-85307.33301 - SFGate

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A member of the Streb Extreme Action Company breaks through a framed panel of mock glass during ground breaking ceremonies for a new Whitney Museum, in New York, Tuesday, May 24, 2011. The nine-story, metal-clad building, which will include a series of asymmetrical rooftops for outdoor exhibitions facing the High Line and the nearby Hudson River, is designed by Italian architect Renzo Piano and will nearly double the museum's current gallery space. less

A member of the Streb Extreme Action Company breaks through a framed panel of mock glass during ground breaking ceremonies for a new Whitney Museum, in New York, Tuesday, May 24, 2011. The nine-story, ... more

Photo: Richard Drew, AP

A member of the Streb Extreme Action Company breaks through a... Photo-1883545.33301 - SFGate

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A Chinese woman dances as a group of people sing revolutionary songs at a park in Beijing Wednesday, May 25, 2011.

A Chinese woman dances as a group of people sing revolutionary songs at a park in Beijing Wednesday, May 25, 2011.

Photo: AP

A Chinese woman dances as a group of people sing revolutionary... Photo-1883546.33301 - SFGate

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TOP SHOTS-Blooming corn poppies stand on a field on May 23, 2011 near Mallnow in the Oderbruch region, eastern Germany. The Oderbruch is a swamp along the German-Polish border river Oder. The land was brought under cultivation after Prussia's King Frederick II. initiated the drainage of the region from 1747 to 1762. less

TOP SHOTS-Blooming corn poppies stand on a field on May 23, 2011 near Mallnow in the Oderbruch region, eastern Germany. The Oderbruch is a swamp along the German-Polish border river Oder. The land was brought ... more

Photo: Patrick Pleul, AFP / Getty Images

TOP SHOTS-Blooming corn poppies stand on a field on May 23, 2011... Photo-1883547.33301 - SFGate

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2011.05.24.13- - A boy at A Child's Garden pre-school in Covedale, Ohio, rides his bike threw the kids car wash Tuesday May 24, 2011, during the 10-year anniversary party for the kids at the school. The kids got to play in the water and have Kona Ice slushees and just hang outside during the school day. (AP Photo/The Enquirer/ Ernest Coleman) less

2011.05.24.13- - A boy at A Child's Garden pre-school in Covedale, Ohio, rides his bike threw the kids car wash Tuesday May 24, 2011, during the 10-year anniversary party for the kids at the school. The kids ... more

JOPLIN, MO - MAY 24: While searching through the rubble of his home, David Vanderhoofven was reunited with his cat Harley on May 24, 2011 in Joplin, Missouri. Vanderhoofven lost his wife Darian Vanderhoofven and son Joshua in the tornado Sunday. Thetornado that ripped through the town of about 50,000 people May 22, is being called the deadliest single tornado in the U.S. in 60 years. less

JOPLIN, MO - MAY 24: While searching through the rubble of his home, David Vanderhoofven was reunited with his cat Harley on May 24, 2011 in Joplin, Missouri. Vanderhoofven lost his wife Darian ... more

Photo: Julie Denesha, Getty Images

JOPLIN, MO - MAY 24: While searching through the rubble of his... Photo-1883549.33301 - SFGate

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A cruise line ship passes by during a sunset in Flatoy island in western Norway, Tuesday, May 24, 2011. (AP Photo/Petros Karadjias)

A cruise line ship passes by during a sunset in Flatoy island in western Norway, Tuesday, May 24, 2011. (AP Photo/Petros Karadjias)

Photo: Petros Karadjias, AP

A cruise line ship passes by during a sunset in Flatoy island in... Photo-1883550.33301 - SFGate

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A plane flies over central London in a sky covered by cirrus clouds as the Icelandic ash cloud moved away from British skies, Wednesday May 25, 2011. High levels of volcanic ash could return to the United Kingdom on Friday just as the bank holiday weekend getaway begins, forecasters have warned. Volcano experts in Iceland said the eruption appeared to be tapering off. Observers at the crater were reporting only steam, said Pall Einarsson, from the University of Iceland. "The worst is over," said Icelandic Prime Minister Johanna Sigurdardottir in a statement, after touring the region around Grimsvotn on Tuesday. less

A plane flies over central London in a sky covered by cirrus clouds as the Icelandic ash cloud moved away from British skies, Wednesday May 25, 2011. High levels of volcanic ash could return to the United ... more

Photo: Lewis Whyld, AP

A plane flies over central London in a sky covered by cirrus clouds... Photo-1883551.33301 - SFGate